You can use virtual servers in any of several distinct ways:

Directing traffic to a load balancing pool

A Standard virtual server (also known as a load balancing virtual server) directs client traffic to a load balancing pool and is the most basic type of virtual server. When you first create the virtual server, you assign an existing default pool to it. From then on, the virtual server automatically directs traffic to that default pool.

Sharing an IP address with a VLAN node

You can set up a Forwarding (Layer 2) virtual server to share the same IP address as a node in an associated VLAN. To do this, you must perform some additional configuration tasks. These tasks consist of: creating a VLAN group that includes the VLAN in which the node resides, assigning a self-IP address to the VLAN group, and disabling the virtual server on the relevant VLAN.

Forwarding traffic to a specific destination IP address

A Forwarding (IP) virtual server is just like other virtual servers, except that a forwarding virtual server has no pool members to load balance. The virtual server simply forwards the packet directly to the destination IP address specified in the client request. When you use a forwarding virtual server to direct a request to its originally specified destination IP address, Local Traffic Manager adds, tracks, and reaps these connections just as with other virtual servers. You can also view statistics for a forwarding virtual server.

Increasing the speed of processing HTTP traffic

A Performance (HTTP) virtual server is a virtual server with which you associate a Fast HTTP profile. Together, the virtual server and profile increase the speed at which the virtual server processes HTTP requests.

Increasing the speed of processing Layer 4 traffic

A Performance (Layer 4) virtual server is a virtual server with which you associate a Fast L4 profile. Together, the virtual server and profile increase the speed at which the virtual server processes Layer 4 requests.

Relaying DHCP traffic

You can create a type of virtual server that relays Dynamic Host Control Protocol (DHCP) messages between clients and servers residing on different IP networks. Known as a DHCP relay agent, a BIG-IP system with a DHCP Relay type of virtual server listens for DHCP client messages being broadcast on the subnet and then relays those messages to the DHCP server. The DHCP server then uses the BIG-IP system to send the responses back to the DHCP client. Configuring a DHCP Relay virtual server on the BIG-IP system relieves you of the tasks of installing and running a separate DHCP server on each subnet.

When you create a virtual server, you specify the pool or pools that you want to serve as the destination for any traffic coming from that virtual server. You also configure its general properties, some configuration options, and other resources you want to assign to it, such as iRules or session persistence types.